Cyclosporine A (CyA)is a drug with a specific influence on the immune system and it is used both to prevent tissue rejection of transplanted organs and to treat autoimmune diseases.The properties, metabolism,and methods of therapeutic drug monitoring (TDM)in patients under immunosuppres- sive therapy are described.TDM of CyA reflects the clinical condition of the patient during immunosuppression and may include pharmacokinetic and pharmacodynamic data obtained either from measuring CyA levels in blood,or from determining some other parameters,which are modulated by CyA (II-2).Although TDM is mainly based on analyzing trough levels of CyA,the determination of the whole biological exposition calculated as AUC enables better correlation with the clinical state of patients.Pharmacodynamic parameters have not been measured routinely yet.

        Key words: cyclosporine A –CyA metabolites –TDM –trough level –AUC